Parasitic-aware integrated substrate balanced filter and apparatus to achieve transmission zeros

Abstract

Described is an apparatus which comprises: a first transmission path for a first frequency band; a second transmission path for a second frequency band different from the first frequency band; a node common to the first and second transmission paths, the node to be coupled to an antenna; and a transmission-zero circuit coupled to the common node.

What is claimed is: 
     
       1. An apparatus comprising:
 a first transmission path for a first frequency band; 
 a second transmission path for a second frequency band different from the first frequency band; 
 a node common to the first and second transmission paths, the node to couple to an antenna; and 
 a transmission-zero circuit coupled to the node. 
 
     
     
       2. The apparatus of  claim 1 , wherein at least one of the first or second transmission paths comprises:
 input ports to communicatively couple to a first die; 
 an input termination impedance coupled to the input ports; 
 an inductor; 
 a first capacitor having a first terminal coupled to one of the input ports, and a second terminal coupled to a first terminal of the inductor; and 
 a second capacitor having a first terminal coupled to one of the input ports, and a second terminal coupled to a second terminal of the inductor. 
 
     
     
       3. The apparatus of  claim 2 , wherein the inductor is a first inductor, and wherein the first or second transmission paths comprise:
 a second inductor inductively coupled to the first inductor, the second inductor having a first terminal which is to couple to ground; and 
 a third capacitor having a first terminal coupled to a first terminal of the second inductor, and a second terminal coupled to the common node. 
 
     
     
       4. The apparatus of  claim 3 , wherein the transmission-zero circuit comprises:
 a third inductor coupled in parallel to the third capacitor of the first transmission path; and 
 a fourth inductor coupled in parallel to the third capacitor of the second transmission path. 
 
     
     
       5. The apparatus of  claim 3 , wherein the transmission-zero circuit comprises:
 a fourth capacitor; and 
 a third inductor coupled in series with the fourth capacitor, wherein the third inductor is coupled to the third capacitor of the first transmission path. 
 
     
     
       6. The apparatus of  claim 5 , wherein the transmission-zero circuit comprises:
 a fifth capacitor; and 
 a fourth inductor coupled in series with the fifth capacitor, wherein the fourth inductor is coupled to the third capacitor of the second transmission path. 
 
     
     
       7. An apparatus comprising:
 a die with a side; 
 a solder coupled to the die along the side; and 
 a laminate based substrate adjacent to the solder, the laminate based substrate having a diplexer embedded in it, wherein the diplexer is communicatively coupled to the die via the solder. 
 
     
     
       8. The apparatus of  claim 7 , wherein the diplexer comprises:
 a first differential transmission path for a first frequency band; 
 a second differential transmission path for a second frequency band different from the first frequency band; and 
 a node common to the first and second differential transmission paths, the node to couple to an antenna. 
 
     
     
       9. The apparatus of  claim 8 , wherein a frequency of the first frequency band is higher than a frequency of the second frequency band. 
     
     
       10. The apparatus of  claim 9 , wherein:
 an input impedance of the first differential transmission path is higher for the second frequency band than an input impedance of the second differential transmission path at the second frequency band; and 
 an input impedance of the second differential transmission path is higher for the first frequency band than an input impedance of the first differential transmission path at the first frequency band. 
 
     
     
       11. The apparatus of  claim 10 , wherein at least one of the first or second differential transmission paths comprises:
 input ports coupled to the die; 
 an input termination impedance coupled to the input ports; 
 an inductor; 
 a first capacitor having a first terminal coupled to one of the input ports, and a second terminal coupled to a first terminal of the inductor; and 
 a second capacitor having one terminal coupled to one of the input ports, and another terminal coupled to a second terminal of the first inductor. 
 
     
     
       12. The apparatus of  claim 11 , wherein the inductor is a first inductor, and wherein the first or second differential transmission paths comprise:
 a second inductor inductively coupled to the first inductor, the second inductor having a first terminal which is to couple to ground; and 
 a third capacitor having a first terminal coupled to a first terminal of the second inductor, and a second terminal coupled to the common node. 
 
     
     
       13. The apparatus of  claim 7 , wherein the laminate based substrate has less than five layers. 
     
     
       14. The apparatus of  claim 7 , wherein the laminate based substrate has a thickness which is less than 30 μm. 
     
     
       15. The apparatus of  claim 7 , wherein the solder is a first set of solder balls, and wherein the apparatus comprises a second set of solder balls adjacent to the laminate based substrate. 
     
     
       16. The apparatus of  claim 15  further comprising a printed circuit board (PCB) adjacent to the second set of solder balls. 
     
     
       17. The apparatus of  claim 16 , wherein the PCB has metal lines with spacing less than 50 μm between the metal lines. 
     
     
       18. The apparatus of  claim 7 , wherein the laminate based substrate is independent of a ground plane. 
     
     
       19. A system comprising:
 a memory; 
 a processor coupled to the memory; 
 a set of solder balls coupled to the processor along a side of the processor; and 
 a laminate based substrate adjacent to the set of solder balls, the laminate based substrate having an apparatus which comprises:
 a first transmission path for a first frequency band; 
 a second transmission path for a second frequency band different from the first frequency band; 
 a node common to the first and second transmission paths, the node to couple to an antenna; and 
 a transmission-zero circuit coupled to the node. 
 
 
     
     
       20. The system of  claim 19 , wherein at least one of the first or second transmission paths comprises:
 input ports to communicatively couple to a first die; 
 an input termination impedance coupled to the input ports; 
 an inductor; 
 a first capacitor having a first terminal coupled to one of the input ports, and a second terminal coupled to a first terminal of the first inductor; and 
 a second capacitor having a first terminal coupled to one of the input ports, and a second terminal coupled to a second terminal of the first inductor.